Fluid-motor.



No. 891,208. PATENTED JUNE 16,1908.

1). CRAIG. FLUID MOTOR. Anuog'nox FILED JUNE 1. 1906.

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No; 891,203. I PATENTED JUNE 16, 1908. D. CRAIG. FLUID MOTOR.

APPLICATION FILED mm 7. 1900.

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DAVID CRAIG, OF MELROSE, MASSACHUSETTS.

FLUID-MOTOR.

Specification of Letters Patent.

Patented'June 16, 1908.

Application filed June 7, 1906. Serial No. 320,525.

To all whom it may concern:

Be it known that I, DAVID CRAIG, a citizen of the United States, and resident of Melrose, in the county of Middlesex and State of Massachusetts, have invented new and useful Improvements in Fluid-Motors, of which the following is a specification.

My invention relates to fluid motors and its object is to provide a motor operated by fluid or liquid pressure capable of developing great power at a relatively low cost and small expenditure of energy.

One of the simplest and most useful embodiments of my invention is in a lift or elevator and I will therefore describe my inven tion as embodied in a lift, but I desire to have it distinctly understood that the invention is capable of many other applications, and is capable of embodiment in other devices for other purposes, and I do not desire to be limited to any specific application or use of my invention, but claim the elements thereof broadly, irrespective of the particular application or use made thereof.

In the accompanying drawings which illustrate diagrammatically an embodiment of my invention in a lift,Figure 1 shows such lift without the sealing and pressure exerting liquid; Figs. 2, 3 and 4 show respectively three different positions of the lift and liquid; and Fig. 5 is a plan View of the lift.

This invention consists essentially in two members A and B relatively movable vertically, the lower member A having a series of upwardly extending walls a forming endless channels between them, and the upper member B having a similar series of downwardly extending walls b forming similar endless channels between them. The walls 7) of the upper member are arranged alternately with the walls a of the lower member, as shown in the drawings, thus forming between the two members a convoluted passage p, extending from within the innermost wall to the exterior of the device and made up of alternately ascending and descending parts or sections.

The two members and their respective walls are preferably cylindrical in form, al-

though it is obvious that they may be made rectangular in lan, or any other shape, so long as the wal s form endless channels between them, and, when assembled or nested together, the two parts form the convoluted passage made u of ascending and descending sections. Iii the drawings three such Walls for each member are shown; that specific number is not essential, but is suflicient to illustrate the invention.

Either the upper member or the lower member may be fixed and the other member movable according to the uses to which the motor is to be put. When the invention is to be used in a lift the lower member is fixed and the upper member movable as illustrated in the drawings.

Communicating with the inner end of the passage 19 is a fluid inlet 0, shown in the drawings as a conduit or pipe which may be controlled by a valve d or in any other suitable way, and is connected with a pump P or other source of pressure. An outlet e may also be provided leading from within the inner wall a. This outlet is also shown in the drawings as a pipe and is controlled by suit able means such as the valve Instead of the separate outlet e provision may be made if preferred for withdrawing the fluid through the pipe 0 and pump P.

I will now describe one mode of operation of the device under certain assumed conditions. It will be understood, however, that such mode of operation is merely illustrative of one advantageous use and condition, and that by varying the kind or quantity of the liquid used within the convoluted passage p, or by varying the pressures introduced within the device, or by varying the arrangement of the liquid columns, presently to be described, diiferent results will be obtained as to the extent of movement and power of the motor or lift. The difference, however, will be quantitative rather than qualitative and the principle of operation of the device will be the same though the physical conditions may be varied. Therefore, a single illustration of the mode of operation under certain assumed and, I believe, favorable conditions, will SHIIIOG.

It will be assumed for the purpose of illustration that the device is to be used as a hydro pneumatic lift for the purpose of elevating a dock or vessel above the normal water level. It will further be assumed that the lower member A rests solidly on the bottom which is 110 feet below the normal water level, W L. The walls a of the lower memher are assumed to be 100 feet in height and the diameters of the respective rings or walls a are 17 feet, 24 feet and 30 feet. The dimensions of the upper member B are appropriate to those of the lower member A to perber within the inner wall I), but I believe that the best results can be obtained by the use of the closure or covering 1). The lower member A is now assumed to be full of water.

The upper member B is then set over the lower member A and forced down to its lowest possible position as shown in Fig. 2 by loading upper member B until its weight, together with the weight of the load, amounts to the largest gross load that the lift will operate under by the method which it is proposed to use. Under the method now being described and under the conditions assumed, such load is found by calculation to be approximately 2162 tons. Compressed air is then forced into the chambers or passages 1, 2, and 3, 4, through suitable inlets indicated at g which are connected with air pumpsor the like, not shown. WVhen the air, pressure in 1, 2 amounts to 73 lbs. absolute, and the air pressure in 4, 5 to 61 lbs. absolute, the columns of water will assume the positions shown in Fig. 2 and the upper chamber B will be in equilibrium between the upward pressure of the air and the downward pressure of its own weight and theweight of its load. With the areas of the various parts above referred to, the total upward pressure of the air amounts approximately to 2162 tons.

Instead of forcing member B down into A, the latter being filled with water, as above described, the members may be assembled as shown in Fig. 2 before any liquid is introduced, and the water and air pressures may then be introduced through inlets c and 9 until the columns of water assume the positions shown in Fig. 2.

The pump P is now set in operation to de liver water into the inner chamber 1 within the inner wall a, at the inner end of the convoluted passage formed between the walls of the two members. It will be observed that at all times the liquid forms seals between the successive convolutions of the passage; thus, the air space in parts 12, is sealed from the air space in parts 34, by the liquid at the lower part of 23 and the air s Jace in 34 is in turn sealed from the atmosp ere (or from the nextpair of parts forming the next convolution in case the number of walls a and b, be increased) by the liquid in the lower part of 4*5. As water is admitted through c to the inner end of a convoluted passage it tends to increase the head of the li uid in parts 1 and 3 by increasing the abso ute volume of water within the in ner wall a, whereby the water meeting the resistance of member B with its load, tends to mount upward in part 1 of the passage, forcing the air, confined in the upper part of 1 over into 2 and forcing the water in the lower part of 2 into part 3 thereby raising the head therein, which in turn forces the air in the upperpart 3 over into 4, thereby forcing the water therein into 5 which, under the assumed conditions, is submerged. If the number of alternate walls a and bwere increased similar results would be obtained in the successive convolutions. .It will now be recalled that under the assumed conditions illustrated in Fig. 2 the hydraulic pressure exerted by the water in the alternate legs of the passage exactly balances the pressure of the upper member B with its load, which rests in equilibrium. By increasing the liquid pressure through inlet pipe 0 and thus causing the columns of waterwhich are exerting the hydraulic pressure to tend to grow, as above described, the upper member B will rise, the pressure of the columns of .water at all times resisting the pressure exerted by B and its load, and maintaining the same in equilibrium. The resistance offered by the sum of the pressures of the columns of water exerting pressure will always be equivalent to the weight of B and its'load plus .whatever counterbalan'cing pressure may result from the waterin passages 2, and 4. As the water is forced into the apparatus the upper member B is thus caused to rise. Fig. 3 shows the position of the water columns and of the upper member B when the latter has been forced upwards 20 feet, in which case by calculation, it is found that the air pressure withinl, 2, is 73.2 lbs., and in 3, 4, is 53.2 lbs. By continuing to supply water through the inlet 0 the upper member B will continue to rise and to assumethe position shown in Fig. 4 which illustrates the position of the columns of water and of the upper member B when the latter is elevated 40 feet. Then the device is in the position. shown in Fig. 4 it is found by calculation that the air pressure in 1, 2' is 73.5 lbs., and in 3, .4 is 46.5 lbs. When in this position the member B will have reached its highest possible point of elevation under the assumed conditions, sincein this position it will be seen that the lower walls a are full of water (while passages 2 and 4 are empty of water) thus exerting their maximum hydraulic pressure. It will be understood that the foregoing description and calculations are based on theoretical conditions.

To lower the member B again to the position shown in Fig. 1, the water is withdrawn from the inner chamber either through the pump P and pipe 0, or through an additional outlet 6, whereupon the operation of the varying pressure conditions will be reversed and the member B will descend.

It is to be observed that it is not essential to the operation of the device, though it is of advantage to secure the greatest efficiency under the conditions assumed, that compressed air should be introduced into the chamber 1, 3 and 5. Neither is it essential that the lower member A should be filled with liquid at the start and the upper member forced therein. The lower member may be empty, as shown in Fig. 1, the upper member assembled therewith, and the liquid effecting the seals and the pressures may all be introduced afterwards through the inlet c in which case a different arrangement of columns will result and a different quantitative effect will result, but the principle of operation will be substantially the same. W' hen the liquid is so introduced at the end of the convoluted passage through pipe 0, it will assume positions in alternate columns in the parts 1, Sand 5 of the passage p; the parts 2, and 4 of that passage will contain air under compression, and the load or pressure supported bythe upper member B will be equivalent to the aggregate resistance of the columns of liquid less such counterbalancing pressure as may result from the liquid being forced to a slight extent into parts 2 and A of the passage and compressing the air therein. A similar arrangement of alternate columns of liquid may be obtained by introducing the liquid at the outer end of the convoluted passage instead of at theinner end. Other means of introducing liquid within the passage 29 may be employed; and other liquids than water may be used, as, for instance, mercury, when the device is used on a smaller scale than that above described, in which case the power of the motor or lift for a given amount of fluid would be increased by the greater specific gravity of the mercury. It is also to be observed that it is not necessary that the fluid forced into the interior of the device, at the inner end of the passage p, through inlet 0, should be water. So long as fluid pressure is admitted, it may be liquid or gaseous.

I claim:

1. A fluid motor comprising two members relatively movable vertically, the lower member having a plurality of upwardly extending walls forming endless channels between them, and. the upper member having a plurality of downwardly extending walls forming endless channels between them, the walls of one member being alternately arranged with relation to the walls of the other member, and forming between the two members a convoluted passage, and means to admit fluid under pressure into said passage.

2. A fluid motor comprising two members relatively movable vertically, the lower member havinga plurality of u wardly extending walls forming endless c iannels between them and the upper member having a and the upper member having a plurality of downwardly extending walls forming endless channels between them, the walls of one member being alternately arranged with relation to the walls of the other member, and forming between the two members a convoluted passage, means to admit fluid under pressure at the inner end of said passage, and means to withdraw fluid from the inner end of the said passage.

4. A lift comprising a fixed lower member having a plurality of upwardly extending walls forming endless channels between them, a vertically movable upper member having a plurality of downwardly extending walls forming endless channels between them, the walls of one member being alternately arranged with relation to the walls of the other member and forming a convoluted passage between the two members, and means to admit fluid under pressure into said passage.

5. A lift comprising a fixed lower member having a plurality of upwardly extending walls forming endless channels between them, a vertically movable upper member having a plurality of downwardly extending walls forming endless channels between them the walls of one member being alternately arranged with relation to the walls of the other member and forming a convoluted passage between the two members, means to admit fluid under pressure into said passage, and means to withdraw fluid from within the inner wall of the lower member.

6. A lift comprising a fixed lower member having a plurality of upwardly extending walls forming endless channels between them, a vertically movable upper member having a plurality of downwardly extending walls forming endless channels between them, the walls of one member being alternately arranged with relation to the walls of the other member and forming a convoluted passage between the two members, means to admit fluid under pressure within said passage and means to relieve the fluid pressure within the convoluted passage.

7. A fluid motor comprising a lower member having a plurality of upwardly extending walls forming endless channels between them, an upper member having a plurality of downwardly extending walls forming endless channels between them, said members being relatively movable vertically, the walls of one member being alternately arranged with relation to the walls of the other mem- 10 pressure at the end of the passage, to assume Signed by me at Boston, Massachusetts,

this fourth day of June, 1906.

DAVID CRAIG.

Witnesses:

ROBERT CUsHMAN, JOSEPH T. BRENNAN. 

